The present invention relates generally to the field of weapon systems and more specifically to encanistered weapon system covers. Specifically, the present invention relates to the field of covers for canisters utilized as storage and launch tubes for missiles.
Historically, encanistered weapon system covers have been designed to be punctured by the nose of the weapon impacting and pushing through the cover material. Such a system greatly simplifies the cover design for most applications.
FIG. 1 illustrates a prior art canister containing a missile. Specifically, canister 12 contains missile 14 for storage and launch purposes. The canister 12 is closed off at its upper end 16 by canister cover 18. It can be seen in FIG. 1 that the nose 20 of missile 14 actually or nearly comes into contact with the canister cover 18. By so placing the nose 20 of missile 14 in contact with or nearly in contact with the canister cover 18, it can be appreciated that when the missile 14 is fired the nose 20 penetrates the canister cover 18 and it can also be appreciated that any exhaust gases or other gases present in the interior compartment 22 of the canister 12 are vented off prior to the accumulation of any deleterious or dangerous vapor pressures. In order to assist in the breakaway of the canister cover 18, it has been common practice to design the canister cover with pre-formed tear lines such as the tear lines 24 illustrated in dotted lines in FIG. 2 which is a top view of the canister cover 18. It can also be appreciated that when the missile 14 exits from the canister 12 during launch, the pre-formed tear lines 24 on canister cover 18 insure that the segments 26, 28, 30, 32, 34, 36, 38 and 40 petal out from central point 42 as the missile 14 exits from canister 12.
Recent cruise missile designs are stored in and launched from an extended canister. It has been discovered that the missile canister must be made substantially longer than the missile due to the missile launcher configuration (not shown) and for survivability of the missile, the launcher and other missiles stored on the launcher. It has been discovered that the missile canisters must be made substantially longer than the missile to insure that the missile is sufficiently far from the launcher upon exiting from the canister to prevent damage to the launcher and other missiles in the launcher. Such damage occurs due to the conflagration or gas explosion and fire which occurs at the exit end of the canister as the missile exits. The longer missile canister avoids the deleterious effects of these conflagration gases.
FIG. 3 is an illustration of the relative lengths of a cruise missile 44 stored in an extended canister 46. In the Ground Launched Cruise Missile System, the extension area 48 of the canister 46 protects the Transporter Erector Launcher (not shown) internal spaces from heat and blast effects when the missile 44 exits the canister 46. More specifically, the missile 44 is stored in the canister 46 within an inert atmosphere such as dry nitrogen. The inert atmosphere within canister 46 is maintained within the canister 46 at a minimum standby pressure such as, for instance, 3.5 psig. When the weapon 44 is fired, it accelerates very rapidly and compresses the gas within the canister 46, the missile acting like the piston of an internal combustion engine. A conventional design canister cover 50 would permit this compressed gas to reach far too great a pressure prior to the nose 52 of the weapon 44 punching through the cover 50 in the conventional manner as described above. This pressure build up within canister 46 would tend to cause the cover 50 to bulge out. More importantly, stress analysis has indicated that the pneumatic pressure accumulation within the canister 46, with a rigid cover, would increase to such an extent and exert forces on the sides of the missile 44 to such an extent that the missile tanks or other compartments of the missile 44 would have buckled. In other words, it has been determined that certain thin-walled compartments of the cruise missile 44 could not survive the buckling force created by this rapid increase in pressure occurring at the time of firing of the missile.